I have never heard of, or at least i dont think i have heard of thiswang. can someone tell me what this is.

thanks

Terkha Dundu is Dudjom Rinpoche´s terma/composition combining 7 lineages of Guruyoga of Padmasambhava, primarily it is based on Guru Chowang's Lama Sangdu combining lineages of Pema Lingpa, Ratna Lingpa, Dorje Lingpa, Zhigpo Lingpa and Dudul Dorje with his own. Dudjom Rinpoche was supposed to reveal a larger cycle of Guru practice, but since the conditions were not favourable, he could not do it. So in place of that Yeshe Tsogyal requested him to write this practice.
If you practice this you can combine it with Dudul Dorje's Gongpa Yongdu for the instructions on ngondro, yidam practice, protectors, tsa-lung and dzogchen, then you will not need anything else. The wang for the practice is really short, it is basically a torwang.